Nothing in my experience varies greatly from what has been summarized in the wiki and other posts above, however I thought it might be useful to others to provide a detailed account of the application process and timing for a new sole proprietorship. My primary recommendation would be that if your online application goes to "under review" and you are in a hurry for a decision don't hesitate to pick up the phone and call. YMMV.

I am an existing Chase customer (5 personal cards) who applied online for an Ink Preferred Business card today. I am 3/24 in terms of recent card applications, but have never previously had a business card. I applied as a sole proprietor following the instructions in this thread, putting down $0 expected business income. (In reality, I do expect to have income, as my business is going to be renting out my house; however, since the rental has not yet started I decided to be conservative and only put down income that I could document, which is $0).

After filling out the application, I got the "under review" message which was then reiterated via email. An hour later I called the 'automated status line' and heard that no application had been received from me. I knew that wasn't true, but because I am an impatient person, about three hours after my application I then called the in-person reconsideration line to see if there was additional info that I could provide in order to expedite a decision. I got the "1-2 weeks for decision" recording but hit 0 to get a live person. The rep ran through several identity verification procedures, and then to my surprise, without asking any further questions, told me that me card was approved. That is to say, I didn't get any questions about what my business is, etc. Granted the credit line is small ($5,000) but that's fine with me for now. And they agreed to expedite shipping of the card, which I was told to expect in 1 to 2 business days.

I will note that prior to my application (i.e. two days ago) I decided to proactively decrease the credit line on one of my personal cards. I know the advice on this thread for doing that is mixed, but that's what I decided made sense for me. Several months ago, when one of my Chase card balances was running high I had requested a credit line increase for that card and to my surprise, was denied. I was subsequently able to transfer credit from a different Chase card without problem, however that experience told me Chase was at or near its limit of the amount of credit it wanted to extend to me. I can't say whether the self-intiatied personal credit line reduction had any effect on either my approval for this card or the relatively small credit line I was granted, but I'm happy with the outcome, and looking forward to earning those 100,000 points!

Thanks to all who have previously posted in this thread, which was very helpful to me.